The primary objectives of the current proposal are as follows: 1.a. To test the hypothesis that smokers characterized by higher compared to lower Anxiety Sensitivity (AS) will demonstrate less success in a self-guided cessation attempt, as indexed by: (1.a.1) Shorter time to first smoking lapse;(1.a.2) Lower point-prevalence abstinence at one, two, four, and 12 weeks post-quit date. 1.b. To test the hypothesis that the association between AS and lapse/relapse to smoking is mediated by the specified emotion and smoking-based processes, including: (1.b.1) Greater levels of negative affect intensity during the cessation attempt;(1.b.2) Greater levels of nicotine withdrawal symptom intensity during the cessation attempt. PUBLIC HEALTH RELEVANCE: The present proposal fills a needed clinically- and theoretically-relevant gap in the smoking- psychiatric literature, as recently espoused by the current NIMH smoking-psychiatric vulnerability report (Ziedonis et al., in press). Indeed, results of the proposed study will directly inform AS-smoking models, and serve more generally as an illustration of how specific anxiety-related processes serve to maintain smoking behavior. The proposed investigation represents a clinically significant and innovative test for a program of research aimed at understanding the mechanisms underlying smoking lapse and relapse.